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<head><meta charset="utf-8"><title>must-use lint · wg-async-foundations · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/index.html">wg-async-foundations</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html">must-use lint</a></h3>

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<a name="165566725"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165566725" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165566725">(May 13 2019 at 20:38)</a>:</h4>
<p>We should extend the <code>must-use</code> lint to suggest <code>await</code> for <code>impl Future</code> values -- has this idea been discussed?</p>



<a name="165566742"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165566742" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165566742">(May 13 2019 at 20:38)</a>:</h4>
<p>(Should I file an issue?)</p>



<a name="165566752"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165566752" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165566752">(May 13 2019 at 20:38)</a>:</h4>
<p>I think it's going to be a pretty important case in practice and probably fairly easy</p>



<a name="165566790"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165566790" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165566790">(May 13 2019 at 20:39)</a>:</h4>
<p>/me sort of still wishes that we had made it an error to "drop" any value that was not type <code>()</code>, but water under the bridge now!</p>



<a name="165566797"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165566797" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165566797">(May 13 2019 at 20:39)</a>:</h4>
<p>/me drags in debates from like 8 years ago</p>



<a name="165567284"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165567284" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> centril <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165567284">(May 13 2019 at 20:44)</a>:</h4>
<p>I think filing an issue is good</p>



<a name="165567317"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165567317" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> centril <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165567317">(May 13 2019 at 20:44)</a>:</h4>
<p><span class="user-mention" data-user-id="116009">@nikomatsakis</span>  ostensibly we can just change the <code>#[must_use ...]</code> message for <code>trait Future</code> ?</p>



<a name="165567354"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165567354" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> centril <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165567354">(May 13 2019 at 20:45)</a>:</h4>
<p><code>#[must_use = "futures do nothing unless polled"]</code> <a href="https://doc.rust-lang.org/nightly/std/future/trait.Future.html" target="_blank" title="https://doc.rust-lang.org/nightly/std/future/trait.Future.html">https://doc.rust-lang.org/nightly/std/future/trait.Future.html</a></p>



<a name="165567458"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165567458" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165567458">(May 13 2019 at 20:46)</a>:</h4>
<p>it seems like it's already implemented</p>



<a name="165567466"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165567466" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165567466">(May 13 2019 at 20:46)</a>:</h4>
<p>er, right</p>



<a name="165567476"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165567476" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165567476">(May 13 2019 at 20:46)</a>:</h4>
<p>you already said that :)</p>



<a name="165567481"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165567481" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165567481">(May 13 2019 at 20:46)</a>:</h4>
<p>yeah, we should just change the message</p>



<a name="165567496"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165567496" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> centril <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165567496">(May 13 2019 at 20:46)</a>:</h4>
<p><span class="user-mention" data-user-id="116009">@nikomatsakis</span> but it doesn't seem to trigger? <a href="https://play.rust-lang.org/?version=nightly&amp;mode=debug&amp;edition=2018&amp;gist=66d2920f7ea5ef6ddd8acfa23d8a2eee" target="_blank" title="https://play.rust-lang.org/?version=nightly&amp;mode=debug&amp;edition=2018&amp;gist=66d2920f7ea5ef6ddd8acfa23d8a2eee">https://play.rust-lang.org/?version=nightly&amp;mode=debug&amp;edition=2018&amp;gist=66d2920f7ea5ef6ddd8acfa23d8a2eee</a></p>



<a name="165567545"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165567545" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> centril <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165567545">(May 13 2019 at 20:47)</a>:</h4>
<p>err, sorry, it does -- I'm just seeing poorly</p>



<a name="165567672"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165567672" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165567672">(May 13 2019 at 20:48)</a>:</h4>
<p>Filed <a href="https://github.com/rust-lang/rust/issues/60797" target="_blank" title="https://github.com/rust-lang/rust/issues/60797">https://github.com/rust-lang/rust/issues/60797</a></p>



<a name="165567822"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165567822" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> centril <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165567822">(May 13 2019 at 20:50)</a>:</h4>
<p><span class="user-mention" data-user-id="116009">@nikomatsakis</span>  thanks; btw, whatever happened to the "good first issue" label? (we had that, right?)</p>



<a name="165567841"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165567841" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165567841">(May 13 2019 at 20:50)</a>:</h4>
<p>yeah, not sure</p>



<a name="165568079"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165568079" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165568079">(May 13 2019 at 20:53)</a>:</h4>
<p><a href="https://twitter.com/nikomatsakis/status/1128040330694017024" target="_blank" title="https://twitter.com/nikomatsakis/status/1128040330694017024">https://twitter.com/nikomatsakis/status/1128040330694017024</a></p>
<div class="inline-preview-twitter"><div class="twitter-tweet"><a href="https://twitter.com/nikomatsakis/status/1128040330694017024" target="_blank"><img class="twitter-avatar" src="https://pbs.twimg.com/profile_images/1110539492706914304/NUeyOrLX_normal.png"></a><p>Want to help the async-await effort in #rustlang and contribute to rustc at the same time? Here's a super easy starter issue: <a href="https://t.co/8ej6mtxT0Z" target="_blank" title="https://t.co/8ej6mtxT0Z">https://github.com/rust-lang/rust/issues/60797</a></p><span>- Niko Matsakis (@nikomatsakis)</span></div></div>



<a name="165568087"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165568087" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165568087">(May 13 2019 at 20:53)</a>:</h4>
<p>I'm guessing it gets closed pretty fast ;)</p>



<a name="165568260"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165568260" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> centril <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165568260">(May 13 2019 at 20:55)</a>:</h4>
<p>heh yeah</p>



<a name="165568847"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165568847" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jake Goulding <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165568847">(May 13 2019 at 21:02)</a>:</h4>
<p><del>See also [this issue]https://github.com/rust-lang/rust/issues/51560)</del> — nvm, I missed the point was to hint on adding <code>.await</code></p>



<a name="165574850"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165574850" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> lqd <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165574850">(May 13 2019 at 22:26)</a>:</h4>
<blockquote>
<p>I'm guessing it gets closed pretty fast ;)</p>
</blockquote>
<p>narrator: it was (and by multiple people concurrently)</p>



<a name="165637155"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187312-wg-async-foundations/topic/must-use%20lint/near/165637155" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jake Goulding <a href="https://rust-lang.github.io/zulip_archive/stream/187312-wg-async-foundations/topic/must-use.20lint.html#165637155">(May 14 2019 at 16:27)</a>:</h4>
<p>Insert obligatory async/await/concurrent pun here.</p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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